By Sophia Byl
In the depths of the mammalian family tree lies a strange and wonderful creature. It has a bill and lays eggs like any bird, but covering its body is the fur characteristic of so many mammals. It also feeds its young with milk, making it one of five animal species on the planet that can make its own custard (known as monotremes). It looks like something drawn by a possessed kindergartener, but in reality, the platypus does much more than just look a little goofy. Actually, the venom that males produce to defend themselves could tell scientists a lot about how to improve modern medicine. Venomous mammals, especially ones as unique as the platypus, are few and far between–and taking a look at their evolutionary lineage reveals some truly fascinating things.
Platypodes (the proper plural form of the word, given its Greek origin) owe their toxic tendencies to modified sweat glands in their hind legs called crural glands, which connect to spurs on their ankles that deliver the venom. This differs from venomous reptiles such as snakes, whose venom glands evolved from salivary glands and therefore transfer venom via a bite. Lots of examples of convergent evolution can be seen between the two different venom systems. Snakes use their bite to defend themselves, but also to hunt–as such, their venom contains proteins that kills and digests body tissue. How does this apply to medicine and pharmacology? Peptides in snake venom have been found to contain properties from killing pain by inhibiting neural pathways to preventing tumor formation by interfering with the adhesion molecules that help cells stick together, or inducing cell lysis.
Compared to the predatory purposes of snake venom, male platypodes use their crural glands as defense against other males during breeding season, not for apprehending prey. Females don’t even have crural glands, and their spurs are vestigial structures. Therefore it would make sense that the compounds in platypus venom serve to cause pain, rather than outright paralysis for something like possible prey.
The sting of a platypus has been described as being “worse than being struck by shrapnel,” in the words of one Australian soldier. But some molecules that make up the mixture that is platypus venom could actually bring about the opposite. At the University of Adelaide, research was done showing that one protein acts similarly to glucagon. Due to negative feedback, the glucagon-like peptide causes the release of insulin–this proposes a solution for those with diabetes. In the human body glucagon deteriorates rather quickly, but the platypus version of it lasts much longer, offering an interesting research path for scientists.
As for the painkilling properties, there is still a lot of research to be done. Scientists at the Australian National University have managed to glean that the venom can switch certain neural pathways on and off, as well as stimulate the release of histamines by mast cells, but they are still in the dark as far as what compounds actually cause what effect. While in use by platypodes, the venom’s job is to prolong and intensify the victim’s suffering, but in the biomedical field scientists are currently looking for a way to exploit those properties to diminish pain. This applies to snake venom as well, which has been a bit more thoroughly researched. But something that applies to both snake and platypus venom proteins is that they are shown to have zero addictive properties as painkillers. If a venom-derived painkiller is created, it could offer a solution to the opioid crisis in our country.
